rc/emacs-rc-common-hooks.el: add *.md to markdown highlighter mode-hook
rc/emacs-rc-screen.el: add dirtracking for 2 parent dirs
rc/emacs-rc-yasnippet.el remove cruft
reorganize snippets for newer yasnippet versions
reorganized snippets
add symlinks for django-/nxhtml-mode pointing to html-mode snippets